1. Field of the Invention
The present invention relates to a cell division tracking apparatus and a method of the same to track the process of cell division on the basis of, for example, a cell image group collected by the use of a microscope, and a non-transitory computer readable storage medium to store a cell division tracking program.
2. Description of the Related Art
Heretofore, in what is known as life-science fields, various cell analysis based on images of cells (hereinafter referred to as cell images) photographed by the use of a microscope have been conducted.
For example, in the studies of stem cells such as ES cells and iPS cells, cell analysis intended for the elucidation of cell differentiation mechanisms and the discovery and development of drugs have been conducted. That is, the following analysis (hereinafter referred to as cell analysis) is conducted in these studies: cell differentiation processes and morphological feature changes are observed on the basis of cell images (hereinafter referred to as a cell image group) collected by time-lapse photography in a time-series manner, and differences in characteristics of cells are investigated.
In the above cell analysis, automation of troublesome operations such as the screening of individual cells that has heretofore been visually performed is becoming possible by the application of image processing technology such as image recognition. If this image processing technology is applied, it is possible for individual cells in the cell image to be discerned, and, for example, to discern morphological features of cells, the number of cells and their changes, and the movement amount and activity degree of the cells by tracking individual cells.
For the analysis of the process of cell division, it is necessary to correctly detect the phenomenon of cell division in the cell image, and correctly recognize the relationship between a cell before division and two daughter cells that emerge as a result of the division. Visually performing the operation of correctly recognizing the relationship requires a significantly complex operation. Therefore, automation of cell analysis that applies an image recognition technique and an image tracking technique has been requested.
Under these circumstances, Jpn. Pat. Appln. KOKAI Publication No. 2007-327843, for example, has been suggested as a technique for tracking cell division. According to the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2007-327843, individual cell regions are specified by cell detection processing from a series of collected cell image groups, a cell feature value is measured for each of the specified cell regions, and the cell regions showing the same cells between frames of the cell image groups are specified among the cell regions on the basis of the cell feature value. During this processing, tracking processing of cell division, that is, processing of associating mother cells before division with two daughter cells after division is performed.
In this tracking processing, neighboring cell regions that are likely to be daughter cells are extracted on the basis of information (e.g., information regarding the distance between the centroids of the regions; hereinafter referred to as relative position information) indicating the positional relation between a cell region targeted for tracking (hereinafter referred to as a tracking target cell region) and cell regions therearound (hereinafter referred to as neighboring cell regions). The cell feature value of each cell region and its change rate are judged on the basis of a preset judgment condition, and the neighboring cell regions that fulfill the judgment condition are specified as daughter cells.